Pattern discriminator

ABSTRACT

A pattern discriminator receives scanning data obtained by raster scanning objects within predefined window regions with a photoelectric converter, converts the scanned data into pixel binary data by using a threshold value dependent upon the scanning position and window region and evaluates the binary data in accordance with predetermined criteria to produce an output signal indicative of the evaluation. A memory stores data which represents the window regions in a compressed arrangement indicating the ordinate and abscissa coordinates of the beginning and ending points or pixels of each window region location on each scanning line, along with corresponding information representing the particular threshold value to be used for each window region segment on each scanning line.

This is a continuation of application Ser. No. 775,800, filed on Sept.13, 1985, now abandoned, which is a division of application Ser. No.483,504 filed Apr. 11, 1983 now U.S. Pat. No. 4,545,070.

BACKGROUND OF THE INVENTION

This invention relates to improvements in a pattern discriminator, andmore particularly to improvements in either a multi-window type patterndiscriminator, or an expanded version of a type of discriminatorreferred to as a template matching pattern discriminator previouslyproposed by one of the present inventors (see Japanese PatentApplication No. 016433, 1982).

In a multi-window type pattern discriminator previously proposed, thecharacteristics of sectional patterns in a plurality of window regionsare set up within a field of vision of a television camera. Thecharacteristics are then quantitatively extracted from binary codedoutputs obtained by processing the time based electrical signals usingpreset threshold levels. The time based electrical signals are obtainedby picking up images of patterns being examined with a photoelectricconverter of the two-dimension sequential scanning type (for example, anindustrial television camera). Subsequently, a range of upper and lowerthreshold limits is set up on a window region basis, and the magnitudeof a characteristic extracted from the scan bears logic 1 if themagnitude is within the range, and logic 0 if not within the range.(This step will be referred to as the first decision step.) Some windowregions are then combined into a group and the combined results of thefirst decision step regarding each window region in a group is comparedwith a preset table of first decision data (the combined results of thefirst decision step for each region constituting each group where goodpatterns exist, having been entered into a table beforehand) in order todistinguish bad patterns from good patterns (this step will be referredto as the second decision step). This second decision step is carriedout for all the groups and then it is comprehensively determined whethera pattern is good or bad based on the above results.

For any groups which have been found bad, a correlative decision step ismade in the next stage, if necessary. The correlative decision step willbe described as follows.

When an examined pattern, even if it is a good one, is slipped out ofthe preset position within the camera's field of vision, the magnitudeof the characteristic extracted from the predetermined window region maynot fall within the range of preset threshold levels. Consequently, thefirst decision step would result in a bad pattern being detected.However, because the pattern has been moved slightly sideward, if thecorrelation between the magnitude of the characteristic detected throughthe predetermined window region and an adjacent window region isobtained, (in this case, the correlation is represented by additions,subtractions and the like) the correlated magnitude obtained iscontained within the range of preset threshold levels and the result ofthe first decision should instead be found good. In view of this, acombination of related proper window regions is chosen, the magnitude ofeach characteristic is operationally processed (for instance, added)between the regions, and the first decision is made on the processedresults (this is called a first correlative decision). A collection ofthe results of the first correlative decision is compared with a presettable of the first correlative decisions (which should be obtainedbeforehand in the same manner as the first decision table) to make asecond correlative decision, whereupon it is determined whether thepattern is good or bad.

To extract the magnitude of a characteristic, it is generally needed toconvert an image signal obtained by an apparatus such as a TV camerainto a binary coded value, and the magnitude of the characteristic isextracted from the binary coded data.

In the above-mentioned multi-window type apparatus, although it issupplied with a number of windows (for example, 32-64 windows), usingonly one binary conversion circuit system with a fixed threshold levelfor converting all image pickup signals into corresponding binary valuesmay not result in obtaining accurate binary data, because the level ofan image pickup signal from the TV camera varies with the portion of theobject if either a shade of color in the examined pattern changesdepending on the portion of the object, or the density of the examinedpattern varies with the portion of the object. In such a case, making adecision on the pattern being examined using improper binary data mayresult in erroneous decisions of the patterns being examined.

The present invention is also directed to a novel means for storing datarepresenting window regions. In this context, a conventional arrangementfor storing window region data will first be discussed.

FIG. 1 illustrates window regions M1, M2 on a picture plane Prepresented by rectangular coordinates X, Y on a two-dimensional basis.When the whole picture plane is raster scanned by scanning the plane Phorizontally in the X direction and vertically in the Y direction, thewindow region generator generates outputs by scanning only in the windowregions M1, M2.

FIG. 2 is a diagram illustrating the relationship between thecoordinates of a window region. In other words, if the window region ofM1 is divided by ordinates along horizontal scanning lines in the Xdirection and the coordinates of the first and last abscissa (X) pointsof the window region are stored, this window region may be representedin storage.

In FIG. 2, for instance, X_(RY1),1 and X_(FY1),1 represent the first andlast points of the window region M1 on the scanning line in the Xdirection along the ordinate Y1. In the subscript RY1,1, the letter Rsignifies a leading point (starting point), Y1 signifies the abscissalocation of this leading point, and 1 signifies that this leading pointis the first leading point on the horizontal scanning line involved. Inthe subscript FY1,1, the letter F signifies a trailing point (endpoint), Y1 signifies the abscissa location of this trailing point, and 1signifies that this trailing point is the first trailing point alongthis horizontal scanning line.

Thus the first point of the window region M1 on the horizontal scanningline along the ordinate a is represented by X_(Ra1), while the lastpoint of the window region is represented by X_(Fa1). On the horizontalscanning line along the ordinate b, second leading and second trailingpoints X_(Rb2), X_(Fb2) occur after first leading and trailing pointsX_(Rb1), X_(Fb1).

When the ordinate is a and the abscissa is X_(Ra1), the window outputsignal value then becomes "1" to open a window and remains at "1" untilthe abscissa reaches X_(Fa1) whereupon the window is closed. Asmentioned above, for the ordinate b, the first leading point of thewindow is located at X_(Rb1) and the first trailing point at X_(Fb1).When the ordinate is b, the window M2 is opened at the second leadingpoint X_(Rb2) and closed at the second trailing point X_(Fb2).

FIG. 3 is a diagram illustrating the arrangement of a window regionstorage memory adopted in a conventional window output generator, andshows an arrangement of data in a memory for the window region shown inFIG. 2. In the arrangement shown in FIG. 3, the leftmost columnindicates the abscissa which starts with 1 and ends with 256 (assumingthat 256 horizontal scanning lines constitute one picture plane). On thebasis of assigning one ordinate value for each scanning line, eachabscissa of the first leading and trailing points and the second leadingand trailing points is obtained and stored as shown in FIG. 3. When aleading or trailing point does not exist, either a mark * is stored toindicate their non-existence or the column is left blank.

Assuming that a one byte (8 bit) capacity is required to store theabscissa of one leading or trailing point, 256 bytes would be needed tostore all the abscissa of the first points for each scanning line, andan additional 256 bytes to store all the abscissas of the last pointsfor each scanning line, so that a total of at least 512 bytes would berequired even for only one window per scanning line. Moreover, if secondleading and trailing points exist (i.e. more than one window along ascanning line), the storage capacity will need to be twice as much. Ifthe unused addresses (marked with *) are compressed and eliminated, onemay not have the flexibility to be able to change the location or numberof window regions to be generated. Therefore, according to this priorart scheme unused addresses may be required if alteration of the numberand/or location of the window region is contemplated. If one attempts togenerate a window region in which a maximum of m leading (or trailing)points exist on the same abscissa a storage capacity of (512×m) byteswill be required, m being normally about 8 and about 16 at maximum.

As mentioned above, because the storage capacity of the memories used ina conventional window output generator is determined by the maximumnumber of the first (or last) points in a window region located on thesame ordinate, the requisite storage capacity becomes enormous and thenumber of peripheral read and write circuits also increasescommensurately, resulting in high production costs. Another disadvantageis that the use efficiency of memories is low because many addresseswill not be used. Still another disadvantage lies in the fact that asthe number of window regions on the same ordinate increases, the abovegenerator lacks versatility from the standpoint of the hardwarearrangement, because the storage capacity must be increased by 512 byteswhenever the number of window regions increases even by one.

SUMMARY OF THE INVENTION

The present invention has been made to improve the prior art and one ofits objects is to provide a multi-window type pattern discriminatorwhich will increase the reliability of the result of a decision even ifthere exists a variable shade of color in a pattern being examined or ifthe pattern density is subjected to change.

In one arrangement of a pattern discriminator according to the presentinvention, binary data are obtained by using different suitablethreshold levels for converting an image signal into a binary value fordifferent portions of a pattern being examined.

An analysis of all the factors which cause the level of an image signalpicked up by a TV camera to fluctuate has revealed that they areclassified into two groups. One group of factors is attributable to theway the apparatus is arranged and the other group of factors isattributable to the pattern characters. Examples of the former includebrightness fluctuation and camera shading. However, properly designedillumination may practically solve these problems.

On the other hand, the group of factors attributable to the character ofa pattern cannot be easily eliminated, and consequently the fluctuationof an image signal picked up by a camera becomes unavoidable. However,the fluctuation in the level of the picked up signal originated in thecharacter of a pattern will be made clear automatically if the patternbeing examined is determined. In the examination and classification ofpatterns, since those being examined are either the same or at leastsimilar by nature, if an object being examined is determined, one candetermine the level at which the signal from the TV camera should be,depending on the portion of the object being examined (i.e., thelocation within the vision of the camera).

The present invention is based on the above-mentioned concept in orderto obtain the most suitable binary data for each window, by providing abinary conversion circuit system with a plurality of channels (forinstance, five channels) each having different threshold levels, and byselecting the proper channel of the binary conversion circuit system foreach of the windows set up on a picture in a multi-window type patterndiscriminator. Preferably, because a number of windows are arranged on atwo-dimensional plane in the multi-window method, the selection of theabove binary conversion circuit is carried out on a two-dimensionalbasis.

Moreover, in the multi-window method, the location and region of awindow are set up on a picture plane in such a way that the basiccharacter and characteristics of a pattern are readily extracted.Accordingly, the most suitable binary signal can be extracted on awindow-by-window basis to obtain accurate data which may be given toprocessors in later stages, despite the fact that the level of thesignal from the TV camera fluctuates depending on the portion andcharacter of a pattern. Moreover, the signal from the TV camera isallowed to pass through different binary conversion channels fordifferent pattern portions even in the same window, so that the signalconverted into a binary value with a different threshold level may beused even within a single window.

According to another form of the invention, a pattern discriminator isprovided for improving the use efficiency of memories to require lessstorage capacity. According to this form of the invention, the means forsetting up window regions comprises a first memory and a second memoryfor storing abscissa data representing respective first and last pointsof at least one window region while dividing and sequentiallycompressing the abscissa data on a scanning line in the X direction inthe picture plane, means for generating data representing the abscissaposition of the scan along each ordinate scanning line, means forcomparing the first abscissa data of the first points in a window regionon a scanning line in the X direction sequentially read out of the firstmemory with the abscissa position data generated by the abscissa datagenerating means, and for generating a window output signal startingwhen both abscissa data conform to each other, and means for comparingthe abscissa data of the last points in the window region on a scanningline in the X direction sequentially read out of the second memory withthe abscissa position data generated by the abscissa data generatingmeans, and for interrupting the window output signal starting when bothabscissa data conform with each other.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a chart illustrating window regions on a picture plane;

FIG. 2 is a chart illustrating the relationship between the coordinatesof two window regions;

FIG. 3 is a table showing the arrangement of memories for storing windowregions in a conventional window region generator;

FIG. 4 is a block diagram illustrating an example of a patterndiscriminator according to the present invention;

FIG. 5 is a table showing the arrangement of memories adopted in thewindow region generator according to the present invention;

FIG. 6 is a diagram illustrating window regions generated by thearrangement of the memories of FIG. 5;

FIG. 7 is a block diagram illustrating an example of a window regiongenerator according to the present invention;

FIG. 8 is a time chart for illustrating operation of the circuit of FIG.7;

FIG. 9 is a diagram of scanning segments in the window regions;

FIG. 10 is a table of the arrangement of memories in the circuit of FIG.4; and

FIG. 11 is a chart illustrating the relationship between a window memoryregion and a characteristic data memory circuit and a window numbermemory circuit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 4, a detailed description of a patterndiscriminator according to one form of the present invention will begiven.

FIG. 4 shows a pattern 101 being examined, a TV camera 102, binaryconversion circuits 103-106 each having different threshold levels, abinary signal (channel) selection circuit 107, a picture plane dividercircuit 108, an AND gate 109, a characteristic extraction circuit 110, acharacteristic data memory circuit 111, a discrimination circuit 112, awindow number memory circuit 113, a memory R/W (read/write) controlcircuit 114, a binary channel memory circuit 115, a window region memorycircuit 116, a coordinate data generator circuit 117, a window outputsignal generator 118, a winoow region generator 119, a timing signalgenerator circuit 120 for generating timing signals to be sent to eachcircuit, and a panel setter 121 for inputting data into memory.

During the operation of this pattern discriminator, the pattern 101 isbrought in by a feeder (not shown) and placed within the field of visionof the TV camera 102. The TV camera 102 converts image data on thepattern being examined into electrical signals in a raster scan manner.The electrical signals are amplified, and are then converted into binaryor digital signals by the binary conversion circuits 103-106, which eachhave different threshold levels.

The threshold level in each binary conversion circuit may be determinedby a fixed threshold method, a floating threshold method, or adifferentiation method. One of the outputs of the binary conversioncircuits 103-106 is selected in the binary signal selection circuit 107to become the binary signal 136. The binary signal selection circuit 107is, as described below, controlled by a selective data signal 137 toselect a signal from the specified channel (binary conversion circuit)107. In this manner, different threshold values can be used forconverting the analog electrical signals into digital data for differentlocations within the region scanned.

The binary signal 136 thus selected is divided into a number of pictureelements or pixels (for instance, 320 pixels×244 pixels in length andbreadth) by the picture plane divider circuit 108. The picture elementsignal is introduced into the characteristic extraction circuit 110through the AND gate 109 only when the AND gate is opened by a windowoutput signal from the window region generator 119.

The characteristic extraction circuit 110 used to extract thepredetermined characteristics of a pattern is a known circuit comprisinga two-dimensional local memory, a two-dimensional local logicaloperation circuit, a counter and other components. A detaileddescription of this circuit is omitted herein because it is not directlyrelated to the present invention. The inputs to the characteristicextraction circuit 110 are limited to what belongs in the window region,and the data on the magnitudes of the characteristics of the patternwithin the window region are extracted and counted. Subsequently, theextracted data are stored in the characteristic data memory 111.

When the scanning of the picture plane has been completed by the TVcamera 102, the discrimination circuit 112 refers to the window numbermemory 113 and totals the characteristic data on a window-by-windownumber basis. The circuit also compares the characteristic data withthreshold levels to determine whether the pattern being examined is goodor bad.

Normally a plurality of windows are provided on the picture planescanned by the TV camera 102. In accordance with the invention, a windownumber is assigned to each separate window, and the window numbers arestored in the memory 113. As mentioned above, provision is made forusing different threshold levels to convert electrical analog signalsinto binary digital values for each window. The threshold level for aparticular window is selected in the selection circuit 107 and inputtedto the characteristic data circuit 111 through the picture plane dividercircuit 109, AND gate 108 and characteristic extraction circuit 110.

A detailed description of the means for generating a window outputsignal according to the invention will be given with reference to FIG. 5and FIG. 6. FIG. 5 shows a descriptive table of memory arrangementsadopted in the window region generator according to the presentinvention. In FIG. 6, window regions (1), (2) . . . (m) exist on ahorizontal scanning line in the X direction on the ordinate Y1. Theabscissas of leading points in regions (1), (2) . . . (m) along thescanning line Y1 are each represented by X_(RY1),1, X_(RY1),2, . . .X_(RY1),m, whereas the trailing points in regions (1), (2) . . . (m)along this scanning line Y1 are indicated by X_(FY1),1, X_(FY1),2, andX_(FY1),m, respectively. In like manner, the abscissas of leading pointsin window regions (1), (2), (3) . . . (l) existing on a horizontalscanning line Y2 in the X direction are shown by X_(RY2),1, X_(RY2),2,X_(RY2),3 . . . X_(RY2),l , while the trailing points are indicated byX_(FY2),1' X_(FY2),2 , X_(FY2),3 . . . X_(FY2),l.

As shown in FIG. 5, the abscissas are divided into two groups, one groupfor leading and one group for trailing points, and the abscissa data arestored in sequential order and compressed. A data byte FF in hexadecimalcode (representing the position of the last pixel on the line) is storedas an abscissa value at the end of each horizontal scanning line.Consequently, the abscissa of the leading points and of the trailingpoints are respectively stored in the left and right columns in thearrangement shown in FIG. 5. Thus, the generation of blank columns(addresses marked with * and not to be used) is avoided as compared tothe case of the conventional arrangement shown in FIG. 3. With theabscissa data stored and arranged in the memories as shown in FIG. 5,the use efficiency of the memories is improved, and the requisitestorage capacity can be minimized.

An example of a window region generator for generating window outputsignals using a memory arrangement like that of FIG. 5 will now bedescribed with reference to FIG. 7, which is a block diagram of a windowregion generator according to the present invention. In FIG. 7, a RAM(random access memory) 1 for storing the coordinates of leading pointsemploys a memory storage arrangement like that shown in the left columnin FIG. 5, while another RAM 2 used for storing the coordinates oftrailing points employs a memory storage arrangement like that shown inthe right column in FIG. 5. FIG. 7 also shows latch circuits 3, 4,comparators 5, 6, an abscissa position generator 7, a FF data detector8, an AND gate 9, and a front/rear pulse generator circuit 10.

FIG. 8 is a time chart used to explain the operation of the circuit inFIG. 7. When a horizontal synchronizing signal H_(SYNC) in horizontalscanning is applied to the front/rear pulse generator circuit 10 from ahorizontal synchronizing signal generation circuit (not shown), thegenerator circuit 10 generates a front pulse F on the front edge F ofthe signal H_(SYNC) and sends this pulse to the RAM 1 and RAM 2, inorder to read out the data representing the leading point abscissaX_(RY1),1 stored in RAM 1 for the window region (1), and the trailingpoint abscissa X_(FY1),1 stored in RAM 2 for the window region (1). Thedata representing the leading point abscissa X_(RY1),1 and the trailingpoint abscissa X_(FY1),1 are latched in the latch circuits 3, 4,respectively, by sending the rear pulse R to the latch circuit 3 and 4with the rear edge of the horizontal synchronizing signal H_(SYNC).Comparator 5 sequentially compares the abscissa of leading pointX_(RY1),1 with the actual abscissa given by the abscissa generator 7 anda high level output signal is generated starting when the two abscissasconform to each other. This high level output signal passes through theAND gate 9 to the front/rear pulse generator circuit 10, allowing thecircuit to output a window output signal thereafter.

Comparator 6 sequentially compares the coordinate of trailing pointX_(FY1),1 with the actual abscissa given by the abscissa coordinategenerator 7 and the high level output signal that has been generated isthen changed into a low level output signal after both abscissas conformto each other. Due to this, the window output signal that has beengenerated from the pulse generator circuit 10 is interrupted, and awindow output signal indicating the window region (1) in FIG. 7 will beseen.

At the time when the comparator 5 compares the input coordinatesX_(RY1),1 from the latch 3 with the actual abscissa position from theabscissa generator 7, and sends a high level signal, indicating thatboth abscissas conform to each other, to the pulse generator circuit 10through the AND gate 9 to generate a window output pulse, the pulsegenerator circuit 10 again transmits a front pulse F and reads the nextabscissas X_(RY1),2 of the next leading point and X_(FY1),2 of the nexttrailing point out of RAM 1 and RAM 2, respectively. When the output ofthe comparator 6 is changed from a high logic level signal to a lowlevel signal as mentioned above, the comparator 5 sends a rear pulse Rto the latch circuits 3, 4 from the pulse generator circuit 10 in orderto latch the abscissas X_(RY1),2 and X_(RY1),2 of the second leading andtrailing points.

Thereafter, the pulse generator circuit 10 sends the window outputsignals corresponding to the window regions (2), . . . (m) in FIG. 8 inthe same manner. Lastly, data FF indicating the end of the onehorizontal scanning line are read out of RAM 1 or RAM 2 and given to thelatch circuit 3 or 4. When the FF data are detected by the FF detector8, the detector output changes from its high level into a low level,causing the AND gate 9 to close.

Subsequently, when the second horizontal synchronizing signal H_(SYNC)is applied to the pulse generator circuit 10, the abscissas of leadingand trailing points on the next horizontal scanning line are read outand latched, so that a window output is again generated. The aboveprocesses are repeated in like manner.

A driving signal EN for starting the operation of abscissa coordinategenerator 7 is preferably applied to the generator 7 when the horizontalscanning reaches ordinate Ys in FIG. 1 for example, to the first windowregion M1. For this purpose, a subtraction counter (not shown) can beused which starts with a preset value Ys, and arranged so thatsubtraction is carried out at the end of each horizontal scanning, andso that the counter outputs a signal when it reaches zero and therebyenables the abscissa position generator.

Referring again to FIG. 4, the relationship between the means forsetting up window regions and the binary conversion circuit will now bedescribed. As shown in FIG. 9, a picture plane 200 is supplied with fourwindow regions P1-P4 and is raster scanned horizontally and verticallyin a conventional manner. Point 201 (marked with °) on the horizontalscanning line Y₁ is the first point of the window region P1, whereas 202(marked with *) is the last point on that line. Similarly, point 203 onthe line Y₂ is the first point of the window region on that line and 204is the last point on that line. Further, point 205 is the first point ofanother window region P2, and point 206 is the last point on that line.Thus the first and last points of the window regions on all the ordinate(Y-lines) are determined and data representative of the abscissapositions of the first and last points are stored in such a manner thata window output signal is generated when raster scanning starts andarrives at the first points of a window region, and are interrupted whenthe scanning is brought to the last point of a window region. Therefore,a window output signal can be obtained which represents the windowregions that have been previously set up.

As described above, the window region generator 119 of FIG. 4 iscomposed mainly of the window region memory circuit 116, the coordinatedata generator circuit 117, and the window output signal generator 118.The abscissa data generator circuit 117 obtains the ordinate on thepicture plane by counting the horizontal synchronizing signals H_(SYNC)133 generated by the TV camera 102 on a horizontal scanning basis andobtains abscissa scanning position data on the picture plane bycounting, for instance, clock pulses at 6 MHz given by dividing, into n,the time period of scanning for one line. The window output signalgenerator 118 generates a window output signal representing thetwo-dimension window regions by comparing data stored in the windowregion memory circuit 116 with abscissa data from the abscissa positiongenerator circuit 117.

FIG. 10 is a chart illustrating the arrangement of window region memory116, binary conversion channel memory 115 and window number memory 113as shown in FIG. 4, using the same reference numbers. In FIG. 10, thewindow region memory 116 consists of an ordinate data memory (116-1), anabscissa data memory (116-2) for storing data representing the leadingpoints of window regions, and an abscissa data memory (116-3) forstoring data representing the trailing points of window regions. Therelative addresses of these three memories are preferably identical, andby using the three data bytes read out with the identical address, dataon the location of the window region segment for that scanning line canbe obtained. In particular, the data in the abscissa memories (116-2),(116-3) are arranged so that the order that the segment data issequentially read out conforms to the scanning order obtained using araster scan.

FIG. 10 shows abscissa data on window region scanning segments for theordinates Y₁ -Y₅ of FIG. 9. For instance, X_(201R) signifies that it isthe abscissa of the first point 201 in the window region P1 shown inFIG. 9, where the letter R signifies a leading or first point, whereasX_(202F) represents the abscissa of the last point 202 in the windowregion P1, where the letter F signifies a trailing or last point.

In the position of the ordinate Y2, the abscissas indicating the firstand last points of the window region are stored in the memory in theorder of windows P1, P2 but, on the abscissa Y₃, in the order of windowsP1, P3, P2 (the window numbers of the windows P1, P2, P3, P4 are assumedto be 1, 2, 3, 4 in window number memory 113). Consequently, if data aresequentially read out of the memory 116, window regions P1-P4 may begenerated on the TV screen as shown in FIG. 9. The reading of data outof the window region memory circuit 116 is carried out by means of thewrite/read control circuit 114.

The following description will be addressed to the relationship betweenthe number of window regions set up on the screen and the selection of abinary conversion circuit so that different threshold levels can be usedin different window regions to convert the electrical analog imagesignals into binary or digital values.

As shown in FIG. 10, the binary conversion channel memory 115 an.d thewindow number memory 113 have a similar arrangement of addresses as thewindow region memory 116. The window number data are stored in thememory 113 in correspondence with the particular coordinate data storedin the memories (116-1, 116-2, 116-3). In addition, the channelselection data in the binary conversion circuits 103-106 are stored inthe binary channel memory 115 in correspondence with the addresses ofthe coordinate data.

Accordingly, it is possible to select a certain binary conversioncircuit having one threshold level for one window region and a differentbinary conversion circuit having a different threshold level for anotherwindow region. As shown in FIG. 10, the channel data representing theparticular binary conversion circuit can be made different for eachwindow number. In FIG. 10, the window number 1 corresponds to the binaryconversion channel data 3, the window number 2 corresponds to the binaryconversion channel data 1, and the window number 3 corresponds to thebinary conversion channel data 2.

Data are sequentially read out of the binary conversion channel memory115 by synchronizing the data with the TV raster scanning with the sametiming as that for reading data out of the window region memory 116 andare latched in the latch circuit (not shown).

The data in the latch circuit, when given to the binary signal selectioncircuit 107, allow the output of the selection circuit 107 to transmit asignal of the selected binary conversion channel to the characteristicextraction circuit 110. Therefore, if the data in the binary conversionchannel memory 115 are selected and stored as required, it will bepossible to obtain a binary value signal 136 by using an individualthreshold level on a window region or subregion basis.

The characteristic feature, as shown in FIG. 10, is that binaryconversion channel data corresponding to the scanning segment of eachwindow have been separately stored. Consequently, different binaryconversion channel data may be stored for different window portions evenwithin the same window, and the outputs of different binary conversionchannels may be selectively extracted Within the same window. It istherefore possible, during processing of an image, to locally change thebinary conversion level within the same window (and this occurs often),and measurements can thus be readily taken with accuracy.

Data can be read and controlled on a realtime basis out of the windowregion memory 116 and the binary conversion channel memory 115 insynchronization with TV scanning. As a result, for each scanning segmentin each window, one optimum binary signal 136 is extracted as shown inFIG. 4, so that the data memory in the characteristic extraction circuit110 can be the same as in the case of one binary conversion circuit,without the necessity of increasing the storage capacity.

Although the output of the characteristic extraction circuit 110 isstored in the characteristic data memory 111, as shown in FIG. 11,characteristic data D_(ij) corresponding to a particular segment (116-2)of the window are stored in the memory 111. Accordingly, thecharacteristic data memory 111 refers to the memory 113 for the windownumber corresponding to that particular window region or subregionthereof and accumulates the characteristic data that belong to the samewindow number. This process, when carried out for all the windows,allows characteristic data to be obtained on all the windows.Thereafter, the discrimination circuit 112 compares the characteristicdata with preset values, gives decisions, and classifies the results.

While the example shows a plurality of binary conversion circuitsprovided with means for switching between them, one comparator may beused to convert data into a binary value by providing a plurality ofthreshold level data for comparison and by switching them from one levelto another.

The panel setting circuit 121 is designed to allow the operator to inputnecessary data to the control circuit 114 and to load the required datainto each memory.

According to the present invention, the following are among theadvantages achieved.

Since any binary conversion circuit may be selected depending on theparticular window or portion thereof, optimum binary image data isavailable in spite of any fluctuation due to camera pattern and of thepattern itself.

Different binary level signals of the binary conversion circuit may beused even within the same window, so that accurate image processing canbe carried out.

The memory can be arranged so that a number of windows can be set up andto have window regions switched and binary conversion channelscontrolled synchronously with TV raster scanning. Consequently, if aplurality of binary conversion circuits are employed, a conventional setof processors can be used to process images in later stages. Also, thetime required for processing is substantially equal to the time requiredusing one threshold level and one binary conversion channel.

Since one need store data only along the scanning lines where the windowregions appear, data for all scanning lines are not always needed. Inother words, it is unnecessary to provide a memory capacity for storing256 bytes corresponding to the total number of scanning lines.

Since the coordinates of the leading and trailing points on the samescanning line are stored in memory regions in a compressed manner, evenif the number of window regions on one scanning line is changed, thememory storage capacity required will not increase significantly; and ascompared to the prior art, the number of bytes will not likely increaseby 256 in order to add just one window region.

By using a data code `FF` to indicate the end of a scanning line, thecoordinates of the first and last points can be stored by compressingthem on a scanning line basis and thereby utilize memory storage moreeffectively.

Since the coordinates of the leading and trailing points in the nextwindow region are read out of memory with a front window edge signal, orwith the front window edge of the immediately previous window region orhorizontal synchronizing signal, the circuitry for generating windows issimple and less likely to malfunction.

The present invention is applicable to pattern inspection, patterndiscrimination, intelligent robots, OCR's and so on in many fields oftechnology.

From the foregoing, it will be observed that numerous variations andmodifications may be effected without departing form the true spirit andscope of the novel spirit of the invention. It is to be understood thatno limitation with respect to the specific apparatus illustrated here isintended or should be inferred. It is, of course, intended to cover bythe appended claims all such modifications as fall within the scope ofthe claims.

We claim:
 1. In a pattern discriminator which receives scanning dataobtained by scanning objects within defined window regions with aphotoelectric converter of the two-dimensional scanning type, and havingmeans for converting the scanning data into pixel binary datarepresenting characteristics of the object scanned by using a thresholdvalue whih is variable within a window region, and having means forevaluating the binary data in accordance with predetermined criteria andfor producing an output signal indicative of said evalution, theimprovements comprising:means for defining a plurality of windowregions, comprising memory means for storing abscissa data representingthe beginning and ending absceissa points of each window region on eachscanning line in a compressed arrangement so that the memory need onlystore data for scanning lines having window regions located thereon,means for generating postional data representing the abscissa scanningposition along each scanning line, comaprator circuit means comprisingtwo comparators, one comparator for comparing the abscissa scanningposition data with the beginning abscissa point data and for producingan output when the abscissa position is after the beginning abscissapoint, and a second comparator for comparing the abscissa scanningposition data with the ending abscissa point data and for producing anoutput when the abscissa position is before the ending point, and logicgate means generating a window output signal in response to theproduction of outputs from the two comparators; means for gating thebinary data to said evaluation means in response to said window outputsignal, so that only binary data for points within a window region areprovided to the evaluation means, and the evaluation means comprising aplurality of binary conversion channels each having a differentthreshold level, and means for selecting from said plurality of binaryconversion channels the output of a particular one for evaluating thesecond data supplied thereto based on the parameter stored in saidmemory corresponding to the address of the data being processed.